In most presidential primaries, there is a candidate who cannot win. All the other candidates want him to finish second because they are sure that if they can get him one-on-one in a runoff, they will defeat him. The victim must have enough intense support to be able to do well in crowded fields  well enough to make the second round. But he must have sharp limits to his potential vote that doom him to failure.

In 1976 it was George Wallace. In 1988 it was Jesse Jackson. In 1992 it was Jerry Brown. In 1996 it was Steve Forbes. In 2000 it was John McCain. In 2004 it was Howard Dean. In 2008 it was Mike Huckabee (who, like McCain, may do better in his second incarnation). In 2012 it was Newt Gingrich and Rick Santorum.

In the Republican nominating process of 2016, it is Rand Paul.

There's no question that Paul has an active and passionate base that will earn him votes throughout the primary process. So he is well equipped to make the second round. But, once there, he cannot win.

Particularly as foreign events continue to remind us that we live in a turbulent and threatening world, Paul's brand of neo-isolationism cannot attract a majority of any electorate in any election. His views seem to predate 1941. While his proposals to reduce the power of the Federal Reserve and his crusade against crony capitalism will win adherents, his support for legalization of drugs, though popular on campus, will turn off voters. His advocacy of a gold standard is either very much behind the times or very much ahead of them. His tepid opposition to abortion and same-sex marriage will appeal to nobody.

The Republican Party is a three-layer cake consisting of economic libertarians, evangelical believers and national security advocates. Huckabee in 2008 showed you cannot win only as an evangelical. He is showing signs of having learned that lesson in his current bid. McCain showed the limitations of a focus on national security. Now Paul is about to demonstrate that economic libertarians cannot win without the other two facets of the party behind them.

In 2016, that is.

As Paul builds momentum and strengthens his organization, he may be able to win in the future. His is an emerging movement based on the increasingly shared consensus reaction to events. Clearly, the factors that are impelling his rise will continue to be felt and grow as the years progress. Americans are indeed getting tired of endless wars in an ever-expanding list of countries against newly hatched enemies. But with each beheading by the Islamic State in Iraq and Syria, we forget our fatigue and are roused to new heights of indignation. And Republican voters are worried that the party's position on abortion is costing it vital support from America's women, ghettoizing it in a white male enclave.

But these trends have more years to grow until they become mature enough to command majorities. Right now, they are good enough only for second-place finishes.

Paul will finish second to Ted Cruz or third to Cruz and Scott Walker among the Tea Party activists. He will be the second choice of economic and fiscal conservatives behind Jeb Bush. Huckabee and Cruz will beat him among evangelicals. Anyone will be more attractive to advocates of national security.

Beyond all this, 2016 is not a year in which Republicans are prepared to gamble. With Hillary Clinton waiting in the wings, who among us is prepared to bet on a new approach to issues and an attempt to reshape our political party? The stakes are too high and the consequences of failure to horrible.